The present invention is an improvement in the field of deployable flotation devices for maintaining buoyancy in marine vessels.
Marine vessels use both permanent buoyancy techniques and deployable flotation systems. Permanent flotation techniques include dedication of compartments within the vessel as flotation or buoyancy tanks. These are watertight compartments permanently sealed and often filled with buoyant foam material. Permanent techniques have the advantage of being in place and require no external agency or power for deployment. On the other hand, permanent techniques take up useful space, sometimes more so than can be tolerated. This is particularly the case with small watercraft where available space is limited. The prior art reveals a number of patents directed to deployable flotation systems to prevent sinking of marine vessels, or to aid in stabilizing powerless boats in rough seas, or to salvage submerged boats.
U.S. Pat. No. 1,448,607 entitled "Insubmergible Vessel" includes an installation in which prestored collapsed floats are inflated with air and deployed along the hull of the vessel to prevent sinking or to aid in raising the vessel if submerged. U.S. Pat. No. 2,918,030 is directed to the use of inflatable containers for raising a submerged vessel. The inflatable containers contain dry ice, for example, which sublimates, forming carbon dioxide for inflating the containers providing buoyancy to a submerged vessel. U.S. Pat. Nos. 3,797,435 and 3,822,662 are both directed to the use of emergency flotation equipment deployed along the broadsides of watercraft for the purpose of stabilizing the craft in rough seas.
The prior art reveals a number of other devices for providing buoyancy to submerged articles or objects. In the case of U.S. Pat. No. 3,556,034 a prepackaged buoyancy system containing a hydrazine gas generator is attached to a submerged object for providing buoyancy.
The traditional method for providing flotation in a boat or vessel has been through use of airtight and watertight compartments. Large commercial or service ships including naval vessels are constructed with bulkheads and bulkhead doors which can be sealed off through use of a screw mechanism connected to door latches. The sealing off of a compartment flooding with sea water will allow maintenance of sufficient buoyancy in the ship to keep her afloat. Construction of air and watertight compartments, however, is expensive and therefore are not used in anything but the largest of vessels. Lifeboats also are used for the saving of life if the ship goes down.
Smaller vessles, i.e., those below 100 feet in overall length, whether motor or sail, have generally not been equipped with sealable bulkheads. Instead, attention has been placed on use of pumps for the vessel and use of personal flotation devices for crew and passengers. Pumps usually cannot be large enough to save a sinking vessel which must be abandoned and allowed to sink even though if saved it could provide a safer and better platform for maintenance of life.
In recent years, beginning in 1978, the U.S. Coast Guard has been charged with maintaining a minimum requirement of level flotation for motor vessels under 20 feet, and the National Motor Boat Manufacturers Association (NMBMA) has adopted standards for motor vessels to 26 feet. But larger vessels are not covered partly because fixed flotation as used in lighter and smaller boats would in larger vessels take up a great proportion of internal space.
Thus, the disadvantages of existing methods can be summarized as:
1. Air and watertight compartments are expensive and not used except in larger vessles.
2. Fixed flotation such as foam-in-place takes up too much internal space to be practical except in the smallest and lightest of craft.
3. Pumps to remove flooding water will work initially but cannot be large enough to save a sinking ship.
4. Life rafts and personal flotation devices save lives but leave a ship to sink.
If the ship is saved it will provide a much better platform for maintenance of life, because food and water are generally available. Moreover, the ship itself will not be completely lost as at present.
Deployable flotation devices have substantial advantage in taking up far less space and are practical to use for life-saving and property salvage. Deployable devices of current design using standard materials occupy too much useful space and can be difficult to inflate and deploy particularly after a vessel is submerged. A typical existing design uses thick rubberized fabric and requires manual connection of air tanks for inflation.